Multiple tunable central cathodes on a paddle for increased medial-lateral and rostral-caudal flexibility via current steering

Abstract

A neurostimulation paddle lead, method of neurostimulation, and neurostimulation system are provided. The neurostimulation paddle lead carries a plurality of electrodes comprising at least four columns of electrodes having a spacing between two inner electrode columns less than a spacing between the inner electrode columns and adjacent outer electrode columns. The inner electrode columns may also be longitudinally offset from the outer electrode columns. The methods and neurostimulation systems steer current between the electrodes to modify a medial-lateral electrical field created adjacent spinal cord tissue.

What is claimed is: 
     
       1. A method of providing therapy to a patient, comprising:
 (a) disposing at least four electrodes adjacent spinal cord tissue of the patient in a medial-lateral electrode arrangement, wherein the at least four electrodes has two inner electrodes and two outer electrodes flanking the two inner electrodes; 
 (b) conveying electrical energy between the electrodes to create a medial-lateral electrical field; 
 (c) discretely moving a locus of the medial-lateral electrical field to one lateral side of the midline of the spinal cord tissue; 
 (d) discretely moving the locus of the medial lateral electrical field to the other lateral side of the midline of the spinal cord tissue; and 
 (e) repeating steps (c) and (d) to repeatedly move the locus of the medial-lateral field back and forth between the one lateral side and the other lateral side of the midline of the spinal cord tissue, whereby dorsal column nerve fibers on both sides of the midline of the spinal cord tissue are stimulated without stimulating the dorsal column nerve fibers along the midline of the spinal cord tissue. 
 
     
     
       2. The method of  claim 1 , wherein moving the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue is accomplished by configuring only a first one of the inner electrodes as a cathode and configuring at least one of the outer electrodes as an anode, and wherein moving the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue is accomplished by configuring only a second one of the inner electrodes as a cathode, and at least one of the outer electrodes as an anode. 
     
     
       3. The method of  claim 1 , wherein moving the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue is accomplished by configuring a first one of the inner electrodes to have more cathodic current than a second one of the inner electrodes, and configuring at least one of the outer electrodes as an anode, and wherein moving the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue is accomplished by configuring the second one of the inner electrodes to have more cathodic current than the first one of the inner electrodes, and configuring at least one of the outer electrodes as an anode. 
     
     
       4. The method of  claim 1 , wherein the medial-lateral electrical field stimulate the dorsal column fibers without stimulating dorsal root fibers within the spinal cord tissue. 
     
     
       5. The method of  claim 1 , wherein the at least four electrodes are disposed within the epidural space of a patient. 
     
     
       6. The method of  claim 1 , wherein the electrical energy is conveyed in a first timing channel to move the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue, and the electrical energy is conveyed in a second timing channel to move the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue. 
     
     
       7. A method of providing therapy to a patient using at least four electrodes disposed adjacent spinal cord tissue of the patient in a medial-lateral electrode arrangement, wherein the at least four electrodes has two inner electrodes and two outer electrodes flanking the two inner electrodes, the method comprising:
 (a) conveying electrical energy between the electrodes to create a medial-lateral electrical field, wherein at least one of the inner electrodes is configured as a cathode, and at least one of the outer electrodes is configured as an anode; 
 (b) discretely moving a locus of the medial-lateral electrical field to one lateral side of the midline of the spinal cord tissue; 
 (c) discretely moving the locus of the medial lateral electrical field to the other lateral side of the midline of the spinal cord tissue; and 
 (d) repeating steps (b) and (c) to repeatedly move the locus of the medial-lateral field back and forth between the one lateral side and the other lateral side of the midline of the spinal cord tissue, whereby dorsal column nerve fibers on both sides of the midline of the spinal cord tissue are stimulated without stimulating the dorsal column nerve fibers along the midline of the spinal cord tissue. 
 
     
     
       8. The method of  claim 7 , wherein moving the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue is accomplished by configuring only a first one of the inner electrodes as a cathode and configuring at least one of the outer electrodes as an anode, and wherein moving the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue is accomplished by configuring only a second one of the inner electrodes as a cathode, and at least one of the outer electrodes as an anode. 
     
     
       9. The method of  claim 7 , wherein moving the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue is accomplished by configuring a first one of the inner electrodes to have more cathodic current than a second one of the inner electrodes, and configuring at least one of the outer electrodes as an anode, and wherein moving the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue is accomplished by configuring the second one of the inner electrodes to have more cathodic current than the first one of the inner electrodes, and configuring at least one of the outer electrodes as an anode. 
     
     
       10. The method of  claim 7 , wherein the medial-lateral electrical field stimulate the dorsal column fibers without stimulating dorsal root fibers within the spinal cord tissue. 
     
     
       11. The method of  claim 7 , wherein the at least four electrodes are disposed within the epidural space of a patient. 
     
     
       12. The method of  claim 7 , wherein the electrical energy is conveyed in a first timing channel to move the locus of the medial-lateral electrical field to the one lateral side of the midline of the spinal cord tissue, and the electrical energy is conveyed in a second timing channel to move the locus of the medial-lateral electrical field to the other lateral side of the midline of the spinal cord tissue.